1. Field of the Invention
The present invention relates to a subject information acquiring apparatus which receives acoustic waves from a subject.
2. Description of the Related Art
Japanese Patent Laid-Open No. 2011-103913 discloses a subject information acquiring apparatus which utilizes a photoacoustic effect, in which acoustic waves from a subject irradiated with light are received with a probe to create an image representing information on the subject. In this apparatus, a breast being the subject is held with two subject-holding members facing each other, and the probe is two-dimensionally moved in horizontal and vertical directions along the subject-holding members to receive acoustic waves. A housing which accommodates the probe (transducer) has an oil sealing portion which enables a matching liquid such as oil to be held between the probe and the subject-holding member for acoustic impedance matching. The upper surface of the oil sealing portion has an opening to remove bubbles contained in the matching liquid. The matching liquid which has spilled or overflowed from the opening runs down the subject-holding member and is then retrieved to a tank by a retrieving mechanism.
The apparatus disclosed in Japanese Patent Laid-Open No. 2011-103913 gives no consideration to the case in which matching liquid flows out of the opening onto the upper surface of the housing (namely, the matching liquid on the upper surface of the housing). Part of the matching liquid on the upper surface of the housing runs down a side surface of the housing and the back surface thereof (opposite side of the subject-holding member relative to the probe). In particular, in the apparatus disclosed in Japanese Patent Laid-Open No. 2011-103913, the matching liquid which has spilled from the opening onto the upper surface of the housing directly falls down from the lower part of the housing without running down the subject-holding member. In the case where the fallen matching liquid does not land on a tray provided below the subject-holding member, the matching liquid cannot be retrieved, leading to possible fear of a decrease in the total amount of the matching liquid. Even in the case where the matching liquid which has not run down the subject-holding member falls on the tray, the matching liquid splashes, which leads to a decrease in the total amount of the matching liquid and makes the interior of the apparatus dirty in some cases.